Circuit Description
WARNING: This page is about a different car, the 2002 Lexus RX 300. However, it is still accessible from the selected car via links, so may be relevant.
MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. If DTC P0101 is set, ECM will operate in fail-safe mode, keeping ignition timing and injection volume constant. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and Engine Coolant Temperature (ECT) sensor indicates more than 158°F (70°C) for 10 seconds or more at engine speed of 900 RPM or less.
DTC P0101 will also set when Throttle Position (TP) sensor output is .63 volts or more, and MAF sensor output is less than 1.06 volts for 10 seconds or more at engine speed or 1500 or more. Possible cause is; faulty MAF sensor.